Getting the XJ12 on the road

With this hot weather we are having in the Pacific Northwest (and my XJS in my shop addressing an oil leak that made a new if my engine bay I detailed last winter), I have a renewed interest in getting my seldom used XJ12 back on the road.

A few issues to sort out:

  1. There is a shudder. I just took it to the tire shop and they balanced the wheels (free of charge, nice of them). I took it for a drive after getting it back. It started out fine. Drove a couple miles on the interstate, exited, drove a couple miles on surface streets, got back on the interstate, and when I hit the brakes the shudder started again. And it’s not just when the brakes are applied, but that’s what starts it. I exited the freeway and continued getting a shudder whether or not the brakes were applied.

  2. “Trac Fail” and “Anti Lock” lights are on.

  3. Upon parking the engine temp crept up and there was a noticable amount of coolant on the ground. It was coming for the bottom side of the header tank (atmospheric catchment tank).

My thinking is

Front brake job for number 1.

Cleaning the wheel sensors for number 2.

And for what I’ve read on here, starting with a new call on the header tank for number 3.

If anyone has any further ideas, please let me know.

Is this an X305, or XJ40 style, or the pukka Series 1-3 XJ12?

(Edit: trac fail is a hint I guess :slight_smile: )

Check the wheel bearings too.

I have a 96 that needs a new front suspension. Looks like a huge job.

1996 x305.

I will take a look at the bearings too.

Hopefully it doesn’t come to a full suspension rebuild. I did the front end of my XJS, can’t be that much more complicated… I hope.

Thanks for the suggestion.

I would check the front calipers. I spent alot of money trying to solve the same problem on my Rolls Royce Silver Shadow. When driving the car (like yours), it would be silky smooth UNTIL I pressed the brake pedal a few times. After that, it drove terribly. Simple to check! Stop the car and touch the hubcap (rim) and see if one is very hot. With mine, the caliper was not releasing because of the brake hose not letting the brake fluid return to the reservior.

Good thought about dodgy caliper. Pad wear will reveal all there.

Thank you, Richard. That was along my line of thought. I was thinking maybe the rotors weren’t true and then the pads were being held a little too close (or progressively getting closer and closer with each press).

It may also be a bad brake disc, warping when it heats up when the brakes are applied. I had that once on my '86 XJ6. New discs and pads sorted it.